Functional aspects, phenotypic heterogeneity, and tissue immune response of macrophages in infectious diseases

de Sousa, Jorge Rodrigues; Da Costa Vasconcelos, Pedro Fernando; Quaresma, Juarez Antonio Simões

Emerging new concepts have recently highlighted the need for a novel approach to our understanding of macrophage response. [34] [35] [36] Similar to T lymphocytes, which feature numerous cellular subtypes, macrophages also differentiate into several phenotypes. 37, 38 Cells belonging to distinct phenotypes are distinguished by expression of groups of markers that define each phenotype. Thorough elucidation of these groups of markers, or panels, has revealed that these phenotypes are distinguished by expression differences in chemokines, chemokine receptors, enzymes, costimulatory molecules, Toll receptors, cytokines, and cytokine receptors. [39] [40] [41] [42] [43] M1 macrophages express inducible nitric oxide synthase (iNOS), the primary marker that confirms the response of these cells in a specific disease (Table 1) . [44] [45] [46] However, a surface marker that defines the identity of M1 macrophages has not yet been identified.